gamma correction

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gamma correction

Adjustments applied during the display of a digital representation of colour on a screen in order to compensate for the fact that the Cathode Ray Tubes used in computer monitors (and televisions) produce a light intensity which is not proportional to the input voltage. The light intensity is actually proportional to the input voltage raised to the inverse power of some constant, called gamma. Its value varies from one display to another, but is usually around 2.5.

Because it is more intuitive for the colour components (red, green and blue) to be varied linearly in the computer, the actual voltages sent to the monitor by the display hardware must be adjusted in order to make the colour component intensity on the screen proportional to the value stored in the computer's display memory. This process is most easily achieved by a dedicated module in the display hardware which simply scales the outputs of the display memory before sending them to the digital-to-analogue converters.

More expensive graphics cards and workstations (particularly those used for CAD applications) will have a gamma correction facility.

In combination with the "white-point" gamma correction is used to achieve precise colour matching.

Robert Berger's explanation of monitor gamma.

["Digital Imaging in C and the World Wide Web", W. David Schwaderer].

gamma correction

An adjustment to the light intensity (brightness) of a scanner, monitor or printer in order to match the output more closely to the original image. A gamma correction imposes the complement of the "tone curve" in order to flatten the line and bring the gamma closer to the ideal 1.0 (see gamma).
References in periodicals archive ?
Both images will also be stretched for contrast and have gamma corrections performed on it.
Other features include DeBayer - colour correction matrix, fast auto exposure, auto white balance, gamma correction and overlay for character and graphics.
Additional image modes include dynamic gamma correction, six-axis color adjustment.
The 20-inch CT-L2000 and 14-inch CTL1400 LCD monitors/receivers feature advanced Al technology that produces lifelike images by processing luminance distribution in real time, with nonlinear gamma correction to boost gradation and luminance where required.
The Image-5MP has the features needed to properly display medical images including 10-bit grayscale for proper display of the gray shades present in the image; calibration and DICOM compatible gamma correction to ensure the highest level of Just-Noticeable-Differences are presented to the viewer; portrait acceleration via hardware for faster performance; grayscale palette support to enable compatibility with many viewer software applications; small form factor PCI bus with dual outputs, enabling multiple dual-head workstation configurations; on-board test patterns for easy access in checking workstation quality; cool, fan-less design for noise-free, long-life viewing.
It features a three-stage electronic zoom and Digital Gamma Correction which improves picture quality in dark scenes or in a brightly-lit room.
Plus ImagePro 2K1 features over 30 tools and filters, such as gamma correction, equalize, sharpen and smooth, rivaling any one of its photo imaging predecessors.
Advanced features include batch scanning of multiple images for maximum productivity, correction tools, real-time preview for transformations and adjustments, an onscreen densitometer and a dropper tool for gamma correction.
Real-time contrast adjustment using Window level, rescale, and gamma correction transforms
In addition, the product reduces optical form factor, and features advances in image processing algorithms, including functionalities related to defect correction, lens shading correction, gamma correction, color correction and interpolation, sharpening filter, low pass filter, backlight compensation, auto exposure, auto white balance, windowing, scaling, and 50/60Hz flicker cancellation, the company claims.